Tuning dielectric properties and energy density of poly(vinylidene fluoride) nanocomposites by quasi core–shell structured BaTiO₃@graphene oxide hybrids

High energy density polymer-based nanocomposites have shown significant potential in modern electronic devices. However, it is still a great challenge to achieve high dielectric permittivity and low dielectric loss without compromising breakdown strength. Here, we report a facile synthesis of core–shell structured BaTiO₃@graphene oxide (BT@GO) hybrids as fillers for enhanced energy density of dielectric polymer nanocomposites. The as-fabricated BT@GO/PVDF nanocomposites manifest high dielectric permittivity and low dielectric loss, as well as highly enhanced breakdown strength and maximum energy density. The nanocomposites filled with 20 wt% BT@GO display a dielectric permittivity value of 14 and dielectric loss of 0.04 at 1 kHz with high breakdown strength of 210 MV/m. As a result, the maximum energy density up to 3.88 J/cm³, which is about 1.6 and 2.1 times higher than that of BT/PVDF nanocomposites with the same mass fraction and neat PVDF, respectively. These well tuned properties are resulted from the novel structure of BT@GO and synergistic effect of the two constituents, which GO shells as buffer layers could effectively mitigate local electric field concentration for enhanced breakdown strength and BT as cores raised the dielectric permittivity. This work provides a potential design strategy based on graphene oxide interface engineering for developing dielectric polymer nanocomposites with high energy density.